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Ramtron FRAM driver

 
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unitrant



Joined: 18 Jul 2005
Posts: 9
Location: Hertfordshire. UK

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Ramtron FRAM driver
PostPosted: Sat May 20, 2006 6:22 am     Reply with quote

The following is a simple adaptation of CCS 24256.c driver to suit the fast handling of the Ramtron 24C256 I2C FRAM. This code is referenced in the test file as FM24c256.c

Code:

// add/remove comments to select speed of I2C bus
//#define I2C_CLK 100000
//#define I2C_CLK 400000
#define I2C_CLK 1000000

#USE I2C(MASTER, FORCE_HW, SCL=PIN_C3, SDA=PIN_C4, FAST=I2C_CLK)

#ifdef __PCH__
   #byte SSPSTAT=0xFC7         // change to suit 18F processor
   #define SMP SSPSTAT,7      // 1=Slew for 100kHz & 1MHz 0=400kHz
#endif

#ifdef __PCM__
   #byte SSPSTAT=0x94         // change to suit 16F processor
   #define SMP SSPSTAT,7      // 1=Slew for 100kHz & 1MHz 0=400kHz
#endif

#define FRAM_ADDR_WR 0xA0
#define FRAM_ADDR_RD 0xA1
#define FRAM_SIZE   32768
#define I2C_WR_ACK 0         // ACK state when writing
#define I2C_RD_NAK 0         // CCS value to NAK on read
#define I2C_RD_ACK 1         // CCS value to ACK on read

void init_ext_fram()
{
   if(I2C_CLK==1000000)
      bit_set(SMP);         // #USE I2C sets incorrectly
}


int1 write_ext_fram(int16 start_addr, int8 data)
{
   int8 result;

   if(start_addr <= FRAM_SIZE)
   {
      i2c_start();
      i2c_write(FRAM_ADDR_WR);
      i2c_write(start_addr>>8);
      i2c_write(start_addr);
      result=i2c_write(data);
      i2c_stop();
      return(result==I2C_WR_ACK);
   }
   return(FALSE);
}


int1 write_seq_fram(int16 start_addr, int8 *pntr, int16 count)
{
   // Does not allow memory wrapping on write
   int8 result;

   if(start_addr+count <= FRAM_SIZE)
   {
      i2c_start();
      i2c_write(FRAM_ADDR_WR);
      i2c_write(start_addr>>8);
      i2c_write(start_addr);
      do
      {
         restart_wdt();      //uncomment if slow speeds
         result=i2c_write(*pntr++);
         if(result!=I2C_WR_ACK)
            break;
      }while(--count);
      i2c_stop();
      return(result==I2C_WR_ACK);
   }
   return(FALSE);
}


int8 read_ext_fram(int16 start_addr)
{
   int8 data;

   i2c_start();
   i2c_write(FRAM_ADDR_WR);
    i2c_write(start_addr>>8);
    i2c_write(start_addr);
    i2c_start();
    i2c_write(FRAM_ADDR_RD);
    data=i2c_read(I2C_RD_NAK);
    i2c_stop();
   return(data);
}


void read_seq_fram(int16 start_addr, int8 *pntr, int16 count)
{
   // memory wrapping is allowed on reads
   i2c_start();
   i2c_write(FRAM_ADDR_WR);
    i2c_write(start_addr>>8);
    i2c_write(start_addr);
    i2c_start();
    i2c_write(FRAM_ADDR_RD);
    do
    {
       restart_wdt();      // uncomment if slow speeds
       *pntr++=i2c_read(I2C_RD_ACK);
   }while(--count>1);
    *pntr=i2c_read(I2C_RD_NAK);
    i2c_stop();
}




And the code below is for testing it:

Code:


#ifdef __PCM__
   #include <16F876.h>
   #opt 9
   #device *=16
   //#device ICD=TRUE
   #device adc=8
   #use fast_io(C)
   #FUSES WDT                 //Watch Dog Timer
   #FUSES HS
   #FUSES NOLVP                    //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
   #FUSES PUT                    //No Power Up Timer
   #use delay(clock=20000000,RESTART_WDT)
   //#use delay(clock=8000000,RESTART_WDT)
   #use rs232(restart_wdt,baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,ERRORS)
#endif

#ifdef __PCH__
   #include <18F252.h>
   #device adc=8
   #opt 9
   #FUSES NOWDT                    //No Watch Dog Timer
   #FUSES WDT128                   //Watch Dog Timer uses 1:128 Postscale
   #FUSES HS                       //8MHz + Osc
   #FUSES NOPROTECT                //Code not protected from reading
   #FUSES NOOSCSEN                 //Oscillator switching is disabled, main oscillator is source
   #FUSES BROWNOUT                 //Reset when brownout detected
   #FUSES BORV20                   //Brownout reset at 2.0V
   #FUSES NOPUT                    //No Power Up Timer
   #FUSES STVREN                   //Stack full/underflow will cause reset
   #FUSES NODEBUG                  //No Debug mode for ICD
   #FUSES NOLVP                    //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
   #FUSES NOWRT                    //Program memory not write protected
   #FUSES NOWRTD                   //Data EEPROM not write protected
   #FUSES NOWRTB                   //Boot block not write protected
   #FUSES NOWRTC                   //configuration not registers write protected
   #FUSES NOCPD                    //No EE protection
   #FUSES NOCPB                    //No Boot Block code protection
   #FUSES NOEBTR                   //Memory not protected from table reads
   #FUSES NOEBTRB                  //Boot block not protected from table reads

   #use delay(clock=8000000,RESTART_WDT)
   #use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,errors)
#endif

#include "FM24c256.c"
  #ZERO_RAM

int8 buffer[64];

void main()
{

#ifdef __PCM__
   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_timer_0(RTCC_INTERNAL);
   setup_wdt(WDT_144MS);
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);
   init_ext_fram();
   set_tris_c(0xBF);
   //enable_interrupts(GLOBAL);
#endif

#ifdef __PCH__
   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_wdt(WDT_OFF);
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_64|RTCC_8_bit);
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);
   setup_timer_3(T3_DISABLED|T3_DIV_BY_1);
   setup_oscillator(False);
   init_ext_fram();
   set_tris_c(0xBF);
#endif

   while(TRUE)
   {
      int16 i;
      int8 j;
      int1 result;

      printf("\r\nTest running...\r\n\r\n");
            
      restart_wdt();
      // high speed write
      for(i=0;i<FRAM_SIZE/64;i++)
      {
         j=0;
         do
         {
            buffer[j]=j++;
         }while(j<64);
         write_seq_fram(i*64,buffer,64);
      }

      result=TRUE;
      restart_wdt();
      for(i=0;i<FRAM_SIZE/64;i++)
      {
         read_seq_fram(i*64,buffer,64);
         j=0;
         do
         {
            if(buffer[j]!=j++)
            {
               result=FALSE;
               break;
            }
         }while(j<64);
      }
      if(result)
         printf("Success\r\n");
      else
         printf("Failure\r\n");
      
   }
}
treitmey



Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA

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PostPosted: Sun May 21, 2006 9:16 pm     Reply with quote

I put a driver in the library also.
A nice feature of mine it that it can span multi chips in the multi-read and multi-write.
http://www.ccsinfo.com/forum/viewtopic.php?t=24099
Christophe



Joined: 10 May 2005
Posts: 323
Location: Belgium

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PostPosted: Wed Mar 21, 2007 2:16 am     Reply with quote

Can this driver be used for smaller memory chips? What changes have to be made?
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